wetware: No dice change here, Thad...as far as I know :-)

That's because you misunderstood Thad's post! He was supposing that in the existing game, with the existing dice, the receiver of the most doubles has the greater chance of winning. It's an intuitively appealing idea but he's asking whether there's any empirical data to confirm it. That's why he gave the post the title Doubles Theory rather than Dice Cheating.

Thad: No dice change here, Thad...as far as I know    :-)

I was just exploring the specific difference that would have resulted from the kind of cheating that took place, according to a news story that I provided a link to (below) a few days ago.

That news story wasn't too clear as to whether just 1 die or both of them were changed, nor did it specify how or when the change was made.

Thad:Someone was caught using altered dice in a European tournament.

Ok, you sorta lost me there. Why are we changing the dice?

nabla: Yes, very good.  And with just 1 die modified, I've finally come up with 8 5/6 pips per roll (in the range you expected).

wetware: Since I counted only two double 5s (the usual one and the former 22) instead of four, I probably missed twice 10 pips, so the grand total would be 336 + 20 = 356, and the average 9 8/9. Better ?

wetware: You are right ! I spotted the trap with one die and fell into it with two dice :-)

wetware: With both dies changed : [ 294 ( = 36 * 7 + 6 * 7, the usual sum of all rolls) + 30 (10 rolls with a 2 changed to 5) + 12 (1 roll with a double 2 changed to a double 5) ] / 36 = 336/36 = 9 1/3. Enough to win most of the long races !

I will leave the "one die" to someone else, but beware, it is higher than halfways between 8 1/6 and 9 1/3.

wetware:
I thought we talk about normal BG without any trick.

Thad: My suspicion was that they'd just make a switch (of one die?  or maybe both--but that would seem too obvious, wouldn't it?) whenever a game was about to become a straight race.  But it might be interesting to test whether a switch made at the start would be a help, as Thad suggested.

Thad:

I would say of course because it's an advantage especially at bear off. But the player should be experienced enough to use the good dice well.

Maybe you can find the verification from the internet.

My conjecture is that players who roll more doubles win more games but does anyone have a way to test that?

I just started this game with dennis and when we started, both identical BKR 2074

nabla: The parallel is that in chess [...]

Yes, I see what you mean now. It's conceptually clean but I still wouldn't implement it because In chess it's game over, while gammons and backgammons occur within the context of a match. My priority for resignations of part of a match would be to score fairly rather than simplistically.

Who would like a sophisticated software to decide about the result of a game ?

Dailygammon already has this in the resignation code. The game is resigned as soon as the outcome is known, with exceptions, I believe, only accounting for the human aspect of playing.

alanback: Exactly. One needs to be sure that one cannot get advantage by resigning or timing out, not that one cannot be disadvantaged by it. The eventually of being forced to play one or two more moves is not much in comparison of being forced to play all those forced moves which could be auto-played...

nabla:  Not worth the effort IMHO.  The contact issue should not be too hard to resolve, but the rest would be difficult and likely error-prone.  Not to mention hard to explain to newcomers.

Except in Triple Gammon, which I don't think should be played here except with long timeout periods, the differences among backgammon, gammon and single game adversely affect only the losing player.  A player can avoid losing too many points by delaying his resignation.  A player who times out doesn't deserve too much sympathy.

alanback: It is the only one as far as I can see. I can't think of any position where there is contact and a backgammon cannot possibly be lost.

But thinking again about single games vs gammons I now see that "one checker off" is not a necessary criteria for gammons to be impossible. If all your checkers are one away from bearing off, and the opponent has more than 5 checkers on the board, one will manage to bear at least two checkers off whatever happens.

So awarding a gammon unless there is one checker off is not 100% conceptually clean after all. It is still probably the best see-in-one-glance estimate. Who would like a sophisticated software to decide about the result of a game ?

nabla:  Indubitably, although this would require some more sophisticated software -- is the contact situation the only one that needs to be dealt with?

playBunny: The parallel is that in chess like in backgammon, there are more than 2 possible results (win or loss). In chess there is the draw as well. So there is the question of what result you get after you time out. And the universally accepted solution in chess is that you get the worse possible result - that is, you get a draw if and only if the rules make impossible for you to lose.

Porting that principle to backgammon would mean that :
- By default, timing out costs a backgammon.
- If a backgammon cannot possibly be lost from the position, timing out costs a gammon.
- If a gammon cannot possibly be lost from the position, timing out costs a single game.

nabla: In chess, if your opponent loses on time and you have one single pawn against an army, you still win the game (if you don't have the pawn, it's a draw

That is an interesting point. You tell me that In chess it's conditional, so why not backgammon? I wonder whether they'd change the rules if there were more than one point at stake? When resigning a chess game the player loses one point because that's the only option. That not the case in backgammon which is precisely why the question remains about when to award what.

nabla:  Good point.  So, resignations in contact situations should always result in a backgammon.

Triple gammon is a special case, and I don't know what to do about that.

playBunny: I agree with everything you said, except that awarding a backgammon when it is still possible seems conceptually clean to me (if not ideal, nor necessarily fair). In chess, if your opponent loses on time and you have one single pawn against an army, you still win the game (if you don't have the pawn, it's a draw).

But the way it is seems acceptable to me, and I certainly wouldn't make a bug record or feature request of it, since there are more important pending ones about backgammon.

nabla: I would discount Triple Gammon anyway as it is a flawed format given that timeouts and resignation have such an impact. Resignation of Triple Gammon matches simply should not be permitted. I don't know what the solution for timeouts is but they can royally screw it up as well. It would be better if there was some way to prevent them or score them fairly.

've no doubt that there are exploits in regular backgammon matches. But even if one were to occur in a tourney final, I still maintain that the excessive potential backgammons would far outweigh the missing actual backgammons.

I think that both ways of doing it are less than conceptual clean but the gammon one is fairer overall in terms of matching unresigned outcomes.

playBunny: Generously awarded gammons ?

But I checked it (easy, just try to resign a game with contact and with no checkers in the opponent's home board, then don't confirm the resign), and you were right, only a gammon is awarded in that case. Somehow my memory played a trick on me, sorry for confusing the debate.

Now it is also true that it seems near to impossible to think of a position with no checkers in the opp's board, where one would be better off resigning a gammon. But IMHO the possibility to do so is still a conceptual bug. And indeed, here is a somewhat contrived situation where it can turn into an exploit :

Triple gammon tournament, there is only one game left to play between the leader and the second. The leader is 4 points ahead of the second, so that he wins the tournament unless he loses a backgammon. To avoid that, he manages to leave the opponent's home board, resigns and wins the tournament. That's wrong.

saeco: he resigned the game and lost a gammon. how is it not an example for the possibility to do just that?

If you had agreed with me then there would have been no query but you agreed with nabla who qualified what I said with the claim that backgammon gets lost if there's still contact. It thus seemed as if you were saying that you had an example where backgammon was awarded.

Frankly I'd be surprised if there a contact-derived backgammon . I don't think BrainKing does that and I don't agree with nabla that it should do that either. If you've escaped your opponent's home then a backgammon is very unlikley. It's by no means guaranteed even with 4 men on the bar. I think the number of generously awarded backgammons simply because there's contact would far outweight any lost points from players who might have won a backgammon but only get a gammon.

saeco:  I apologize if I misunderstood.  However, IMHO contact has nothing to do with the way points are awarded for a resignation.  Nor should it.  Points are properly awarded based only on the position of the resigning player's pieces.  A different rule would permit manipulation.  For example, suppose a player has not borne off and has one checker on his opponent's ace point.  The opponent has borne off all but one checker, and it sits on the opponent's two point.  The trailing player rolls the dice and gets 3-2.  If he plays the roll and his opponent moves, he is guaranteed to lose a backgammon.  He should not be able to resign (or time out) and lose a single game or a gammon.

If a player wants to avoid losing a gammon in a contact situation -- or even in the absence of contact -- he has to play until he has borne off a piece.

There are sites where a player can offer to resign a single, a gammon, or a backgammon.  This turns out not to work very well, because players may offer to resign for fewer points than the opponent is entitled to, inadvertently or intentionally.  If the opponent isn't watching carefully, he may accept and then feel (perhaps rightfully) that he was cheated.

alanback: In this game I shouldn't even have lost a gammon... ;) Well if you always lose 5 points on a timeout I think that should be stated on the Triple Gammon rules page, shouldn't it?

Gordon Shumway:  You certainly should not have lost a backgammon.  Now that you mention it, I think all timeouts in Triple Gammon are awarded 5 points.  But I don't think the backgammon would be awarded outside Triple Gammon, and saeco's post is an example of that.

alanback: i think i kind of missed your point. i just thought that you couldn't resign and lose (just) a gammon even if there wasn't any contact and you were clear of your opponents home. then i found the game i posted as an example for the possibility to do that.
but of course, if there is contact you can't resign and lose just a gammon.

saeco:  Because you are correct that he lost a gammon (2 pts).  The score was 4-1 before the game started and 6-1 afterwards.  He cited it as an example of a backgammon (3 pts).  He also said that the result was impossible if the game were played out, which is incorrect; gammon was not only possible, but likely.

saeco: but do you actualy lose a backgammon for a timeout even if it wasn't possible to lose one if the game was played till the end?

Not on all occasions. If you alredy moved a piece off the board, then you aren't going to lose a gammon I think, but if you didn't - well, then it's backgammon time. I lost 5 points in this triple gammon nack game on a time out for example:

Nackgammon (netvenus vs. Gordon Shumway)

playBunny: he resigned the game and lost a gammon. how is it not an example for the possibility to do just that?

saeco: How is that an example?

nabla: yes, that's how it's done. for some reason i thought the resign-function was messed up on brainking. (and never resigned in those situations) but i found an example of it: Backgammon (kd5svqJT vs. saeco)
but do you actualy lose a backgammon for a timeout even if it wasn't possible to lose one if the game was played till the end?

nabla:  I hadn't thought about the contact part -- though one would rarely resign in such a case.  Otherwise, nabla and pB have got it right.  

playBunny: If you resign when you're clear of your opponent's home then you'll be asked to confirm losing a gammon.

Yes, except that you need to be clear of your opponent's home AND there needs to be no contact any more (otherwise a backgammon could still be lost after a hit). This is how it should be and to the best of my memory how it is - I will soon have the occasion to check it for real :-(

saeco: i think that a resign means you lose a backgammon as long as you haven't moved out any piece

You mean moved a piece off the board? No, it's a backgammon only if there are pieces in the opponent's home or on the bar and none of your own already borne off.

iirc, you can't resign and lose a gammon

If you resign when you're clear of your opponent's home then you'll be asked to confirm losing a gammon.

saeco: I think you're right although I haven't tried it, because I guess it will work similar to the time outs - and I once lost 3 points on a timeout when there was no confrontation on board and noone had a huge edge, so a backgammon was impossible and a gammon close to impossible.

playBunny: iirc, you can't resign and lose a gammon. i think that a resign means you lose a backgammon as long as you haven't moved out any piece - even if a backgammon would be technically impossible at the time. of course the option to resign a game as a gammon would be good, but i don't think we have it here.

coan.net: As a side note for cube games, I'm pretty sure you are given the points where the current pieces are

You are.

...so a early resignation will lose the person a gammon.

It'll be a backgammon until the backrunners are clear of the opponent's home and that's often way into the mid game and later.

Andersp:
Oops! my bad! I didn't realize it was a 5 game match and not a 5 point match. That makes all the difference in the world. I guess I was having a blonde moment so to speak and was looking more forward to the rare backgammon... My apologies!

LionsLair: Yup - like Andersp said - it is a 5 WIN match - does not use the cube, so even if you won by a gammon, you would still only get 1 win.

As a side note for cube games, I'm pretty sure you are given the points where the current pieces are - so a early resignation will lose the person a gammon.

Andersp: lol I didn't look at the game, good point Andersp, a gammon etc in those type of games is irrelevant.

LionsLair: Can you get 3 points in a 5 win match without cube?

LionsLair: you didnt have to accept the resignation.

Today I learn that you could avoid a backgammon by resigning the game as my opponent did in this game.
Backgammon (LionsLair vs. AlliumCepa)
Thus only giving up one point instead of 3. I'll have to use this info for future reference when I find myself in that situation. Tis a sad way to play in MHO, but if the system lets you... as the old saying goes, if you can't beat 'em, join 'em!